1. Field of the Invention
This invention relates to emergency lighting systems that provide illumination for buildings and the like during power failure, using an emergency power source and selected fixtures or luminaires within a larger lighting system.
2. Description of Related Art
In the past, safety codes required that emergency luminaires that are powered by an emergency generator or inverter during a power outage must be illuminated 24 hours per day, 7 days per week, to give a continual indication of their readiness and operability. In recent times, the codes have been changed to permit the use of a power transfer control (listed under UL924 specs) to turn on and off both the regular and emergency luminaires at the same time. During a utility power failure or room power interruption, only the designated emergency luminaires are illuminated automatically, using the emergency power source, regardless of the on/off position of the room lighting switch.
This arrangement is more economical and convenient, but it does not provide the continuing assurance of emergency lighting readiness that was given by the older systems. As a result, it is necessary to provide a test feature and readiness indication for systems that use the power transfer control arrangement. Generally, this requirement is met by turning off the lighting branch circuit breaker that serves a particular area, which in turn automatically transfers the emergency light fixtures in that area to an emergency power source. This test routine involves visiting each lighting panel, and is time consuming.
Intelligent building operating systems may incorporate sensors and subroutines to survey the emergency lighting systems in a building, and report problems or failures. These systems, however, may not fulfill code requirements for personal inspection of the systems and the individual responsibility it conveys. Nor do they provide the conclusive determination of eyewitness observation of proper testing of an emergency lighting system.